Refactor the app to use a proper backend

[vstrimaitis]

Currently, all logic is running in the frontend. The data is served as massive json files. It would be smart to move all of this data to some back end service and expose some REST endpoints that the front end could consume.

The main problem is hosting. Investigate hosting / storage options (heroku / azure / ???). If any of those is good enough to be used, the app should be refactored.